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...Non homogeneous equations sect we study y p t q f method of variation parameters using the in an example proof parameter another remarks this is a general to nd solutions having variable coecients and with continuous but otherwise arbitrary source function can be applied more than undetermined usually takes time implement simpler theorem let r functions linearly independent equation w wronskian if u are dened by z dt then particular solution find inhomogeneous et first fundamental characteristic hence compute their second denition yf recall e third c denote l weneed yp weknow idea reduction order proposing uy propose that given wehope for will original since...